THE COTTON WORM OR COTTON CATERPILLAR. 5 



The larva. — The larvae of the cotton moth vary greatly in size and 

 coloration, but there are certain characteristic marks that enable one 

 to determine the species. (See fig. 1.) Early in the season the 

 larvae are yellowish-green and not provided with conspicuous mark- 

 ings. As a matter of fact, individuals without conspicuous markings 

 may be found in the cotton fields throughout the season. The form 

 generally seen, however, may be described as follows: T^ength about 

 IJ inches, upper surface with a broad brownish or perfectly black 

 stripe. Down the center of the stripe is a fine yellowish line and 

 similar lines bound the black area on either side. Each segment as 

 seen from above shows four black dots, which, of course, are much 

 more conspicuous where the dorsal black stripe is less distinct. When 

 viewed from the side each segment shows four black dots similar to 

 those on the dorsal surface, but somewhat smaller in size. 



The larvae feed by preference upon the cotton leaves. In cases 

 where they are so abundant that the leaves are destroyed they feed 

 upon the squares and bolls and even the twigs. In the case of attack 

 on bolls only the outer surface is devoured. On this account the 

 work of the cotton worm on bolls can be distinguished from that of the 

 boll worm. The latter species gnaws a hole directly through the out- 

 side of the boll and feeds upon the interior. 



Careful investigations have shown that the cotton worm feeds only 

 upon the cotton plant. In many cases where attempts were made to 

 breed it on other plants failure resulted. In one instance Mr. E. A« 

 Schwarz succeeded in causing a larva to develop to the chrysalis stage 

 on morning-glory (Ipomoea sp.). The chrysalis, however, was imper- 

 fect and failed to develop. The statement is frequently made that 

 the cotton caterpillar feeds upon pokeweed (Phytolacca sp.) and other 

 plants. Such reports are due to mistaking some other insects for the 

 cotton pest. 



When the worms are numerous and a cotton field has been defo- 

 liated they frequently travel over the ground in great numbers in 

 search of food. This habit is the cause of the local use of the term 

 "army worm" for the insect. 



The chrysalis or pupa. — The cotton caterpillar transforms to the 

 pupal stage on the cotton plant. Unlike the bollworm, it never enters 

 the ground for this purpose. Usually it spins a crude web, using a 

 portion of the cotton leaf for the purpose, but in many cases no web 

 whatever is formed, and the naked pupa hangs from the cotton plant 

 by means of a thread spun by the larva for the purpose. (See fig. 1.) 

 The duration of the pupal stage is from one to four weeks. 



The adult. — The adult of the cotton worm is a moth, the wings of 

 which expand from IJ to 1^ inches. (See fig. 1.) The general 

 color is brownish-yellow or tawny, in many specimens showing a 

 somewhat crimson hue. The most conspicuous feature of the upper 



